Compressor-unloader.



L. IVERSEN. COMPRESSOR UNLOADER.

APPLICATION FILED JUNE 9, 1913.

Patented Dec. 29, 1914.

Q iir m x A k mnQ I W I 1 I- ..W. 0 1 N .l N A r 1% m\ m Q N N\ N) b R Qfix n R \S INVENTOR K We lld

LORENZ ZVEFJSEN, 0E WEST HOMESTE er a PENNSYLVANIA.

CQRESSOR-UNLOER.

specification of Letters Patent.

Patented Dee. as, rare.

Application filed June 9, 1913. Serial No. 772,520.

To all whom it may concern Be it known that I, LORENZ IvERsnN, a citizenof the United States, and resident of West Homestead, in the county .ofAllegheny-and State of Pennsylvania, have invented certain new anduseful Improvemerits in Comp essor-Unloaders, of which the following isa specification.

The object of this invention is to provide simple and highly eficientmeans for proportioning the load to the demands upon the compressor,provision being had for either partially pr completely unloading themachine by gradually decreasing the efiectiveness of the pumping strokesas the pressure at the discharge approaches a predetermined maximum, thepartially or wholly inactive strokes again. becoming active withincreased demand upon the machine. Thus, the whole, or one-half or anylarger or smaller fractional part of each stroke of e piston may berendered inefiective, the

unloading being -accomplished gradually and the machine saved theinjurious shockresulting from a sudden and complete un-' loading.

and B communicating with opposite ends of the cylinder, and dischargevalves and 6 for establishing communication between the oppositecylinder ends and the cylinder. discharge 7, a pipe or header 8 passingthe compressed air to a receiver orotherstoring or pressure utilizingmeans, not shown. The cylinder is here shown provided with twointermediate inwardly opening valves C and D so spaced between the endsof the cylinder that when either of said valves is I open it' rendersinedective one-half the stroke of the. piston in one direction. Valves Aand B may be the usual inlet valves, or two ofsuch valves if there ismore than one'inlet at each end. In the present adaptation each inlet orrelief valve is pro- -tion to engage the valve plate V and hold it open,the arms being secured to a piston 11 in cylinder 12, a spring 13holding arms and the piston normally retracted. Pipe 14 is adapted toestablish communication between each cylinder 12 and a pipe 15 in whichthe pressure at the discharge side of the machine is maintained, beinghere shown connected to the cylinder discharge 7, though it will beunderstood that it is immateri'al where or how the connection'is made solong as the efiective pressure is communicated to cylinders 12. Each ofthe cylinder connections 1ft is provided with a pressure regulatingdevice of which various forms are known in the art.

Qperation: If pressure of approximately 100 pounds is to be maintained,the regulator C for valve C may be set to open at say 98 pounds, theregulator D for valve D at 100 pounds, B for valve B at 102 pounds, andA for valve A at 104 pounds. 1f the demands upon the compressor are suchthat the maximum pressure is sustained with only one-half of eachalternate stroke of the piston efi'ective, then valve C is held bpen, asshown in the drawing, by a pressure of 98 pounds, and rendersinefl'ective the first half of the stroke of the piston when moving tothe right, the'latter half of that stroke and the full stroke in theopposite direction being efi'ective. It the discharge pressure attains100 pounds notwithstanding -the open valve C,'then valve D opens andrenders inefl ectiveone-half of the stroke to the leftyand with valves-Cand D both open, only one-half of each. stroke is effective. If theunloading thus accomplished is not 'suilicient the: increase ofdischarge pressure opens valve B at 102 pounds, thusleaving onlyone-fourth of each. alterhate stroke active, or when the piston ismoving from valve C toward valve. A. If there are n'odemands upon thecompressor and the-pressure rises to 10d pounds, then valve A is openedwith the result that no portion of either stroke is efi'ective, the airsimply churning in and out through the valves which are open to theatmosphere. The relief valves may be variously constructed and variouslypositioned at and with between the cylinder ends in any desired numberand in such location as to relieve all or any fractional part or partsof the compressing'strokes. In machines of such 'size asto require aplurality of inlet valves at each end of the cylinder, only such numberneed be utilized for unloading as are required to prevent accumulationof pressure. Nor is the invention restricted to the use of only a singlevalve at each intermediate position, as it is obvious that as many maybe utilized as may be necessary to automatically proportion the load tothe demands upon the machine.

it claim 1. The combination of a compressor cylinder, a relief valve incommunication with the cylinder intermediate the cylinder ends,automatic means for operating the relief valve when predeterminedcylinder discharge pressure has been attained, and, a piston within thecylinder and adapted to close the communication between the cylinder andvalve during a portion of the piston stroke.

2. The combination of a compressor cylinder, a relief valve incommunication with; the cylinder intermediate the cylinder ends, meansactuated 'by cylinder discharge pressure for operating the valve whenpredetermined cylinder discharge pressure has'been attained, and aistonwithin the cylinder and adapted to c ose the communication betweenthe cylinder and valve during a portion of the piston stroke. 7

3. The combination oi a compressor cylinder and piston, a plurality ofrelief valves in communication with the cylinder at different points inthe length of the latter, and

means actuated by difierent cylinder discharge pressures for operatingthe respective valves.

A 42. The combination of a compressor cylinder, end and intermediaterelief valves in communication, respectively, with the cylinder at itsends and between its ends, means actuated by difierent cylinderdischarge pressures for operating the respective valves, and a pistonwithin the cylinder and adapted during predetermined portions of itsstrokes to close the communication with the intermediate relief valves.

5. The combination as a compressor cylinder and piston, end andintermediate relief valves in communication, respectively,

inder and piston, inlet'valves for thefo with the cylinder at its endsand between its ends, and means. actuated by difierent cylinderdischarge pressures for opening the respective valves with theintermediate valves adapted to open under lower pressures than the endvalves. j

6. Thecombination of a' compressor cylinder, an automatically closingrelief valve in communication therewith intermediate the cylinder ends,a device operated by fluid pressure created in the cylinder for openingsaid valve, and a iston within the cylinder and adapted to cosecommunication with the valve during a portion of the" piston stroke.

'7; The combination oi a compressor cyl inder, a relief valve incommunication therewith intermediate the cylinder ends and adapted toopen against cylinder pressure, a device operated by predetermined fluidpressure created in the cylinderior opening said valve and for holdingit open while such pressure is maintained or exceeded, and a pistonwithin the cylinder and adapted to close communication with the valveduring a portion of the piston stroke.

8. The combination of a compressor cylinder and piston, a, plurality ofautomatically closing reliei valves in communication with the cylinderat different points in the length thereof, and devices one' for ca hvalve-operated, respectively, 1 by 'difie'rent predeterminedpressurescreated in the cyl= inder for opening said valves.

9. The combination of a compressor clder with certain of said valves incornrnu' cation with the end portions of the cylii and with other inletvalves positioned termediate the cylinder ends to render i'ectivepredetermined portions of the pi stroke when predetermined pressure beenattained in the cylinder dische pressure actuating means for each valvefor holdin the same open, and means for communicating varied and l minedpressures from the cylinder'disc to the respective inletvalves.

In testimony whereof I ar -fix my signature I in presence of twowitnesses.

LQRENZ TV.

Witnesses:

J. M. Nnsnrr, F. E. Garrmn.

